Feasibility of estimating peanut essential minerals by near infrared reflectance spectroscopy

The use of near infrared reflectance spectroscopy (NIRS) to evaluate the nutritional quality of peanut kernels has potential applications in plant breeding as a rapid, non-destructive tool for seed/plant selection, and in quality control. We investigated the feasibility of applying NIRS to the estimation of essential mineral composition in peanut kernels using two sample sets: A, comprising 56 diverse genotypes (N = 163); and B, comprising nine genotypes grown in five distinct environments (N = 156). Essential mineral composition was analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and -mass spectrometry (ICP-MS). Calibration models were developed by partial least squares (PLS) regression, and explored a variety of data pre-treatments. Models allowing approximate estimation of K (RPD_CV 2.25, r_CV² 0.800, RPD_P 2.22) and Mg (RPD_CV 2.24, r_CV² 0.786, RPD_P 1.74), and to a lesser extent Ca (RPD_CV 1.85, r_CV² 0.649, RPD_P 1.52) and P (RPD_CV 1.77, r_CV² 0.634, RPD_P 1.65), were developed for Set B, but poorer calibrations were obtained for Set A. This level of accuracy does not allow accurate prediction, but permits approximate quantification that may be useful in plant improvement programs for screening breeding populations. The results are remarkable because NIRS is rarely applied to analytes present at such low concentrations, especially inorganic constituents that are not inherently NIR-absorbent. Further analysis of more diverse peanut samples is warranted to confirm batch-to-batch accuracy and to improve the robustness of calibrations.     

Smart and structural thermosets from the cationic copolymerization of a vegetable oil

Copolymers based on tung oil (TO) and presenting a very wide range of properties were obtained. Depending on the chemical composition, materials fitted for structural or functional applications were prepared. The use of divinylbenzene (DVB) as a comonomer in the cationic polymerization of the triglyceride allowed us to obtain polymers with a high thermal stability in an ample temperature range and with a room‐temperature modulus close to 1 GPa for percentages of TO up to 40 wt % styrene (St) as a partial replacement of DVB in a copolymer containing 50 wt % TO resulted in a material with shape‐memory behavior with switch temperatures in the range 25–40°C. The mechanical properties and shape‐memory behavior of copolymers with different chemical compositions were analyzed. It was observed that an increase in the DVB content increased the glass‐transition temperature and modulus, which was associated with an increase in the crosslinking density and the contribution of the rigid aromatic structure of the comonomer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of crosslinking on the properties of sodium caseinate films

Protein films are used as effective lipid, oxygen, and aroma barriers at moderate relative humidity conditions. However, they perform poorly as moisture barriers. The introduction of crosslinks within or between protein chains by enzymatic or chemical modification has been proposed as an alternative means to achieving a stronger polymeric matrix structure, which would result in better functional film properties. In this article, we report the preparation and characterization of sodium caseinate (SC) films crosslinked by glutaraldehyde (GTA) or heat. The crosslinking density increased with GTA content. The thermal stability and tensile modulus and strength increased with GTA content, although films with a low crosslinking density exhibited lower properties than the uncrosslinked sample. Unexpectedly, water vapor permeability and absorption also increased with crosslinking density. The crosslinking of SC was also induced by simple heating. The resulting films showed enhanced thermal, mechanical, and barrier properties compared to the unmodified SC films and even the GTA‐crosslinked samples. GTA crosslinking was unable to reduce the high hydrophilicity of the SC films. Thermally induced crosslinking was revealed to be a valid alternative for improving the properties of SC films, without the inherent complications associated with the use of a chemical crosslinking agent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Nanocomposites made from cellulose nanocrystals and tailored segmented polyurethanes

The effect of the addition of microcrystalline cellulose nanofibers into linear segmented polyurethanes (SPU) was investigated. The polymers were synthesized with 4,4‐methylene‐bisphenyldiisocyanate (MDI) and poly(tetramethyleneglycol) (PTMG) with 1,4‐butanediol (BD) as chain extender. The nanocrystals were introduced during the PU polymerization, which resulted in cellulose nanofibrils covalently linked to the polymer. The interactions between the cellulose nanofibrils and the matrix lead to interesting changes in the behavior of the PU, with the hard segment (HS) phase being more affected by these interactions. SPUs with different contents of HS were synthesized to better understand these effects (23 to 45 wt %). Thermal, thermo‐mechanical and mechanical characterization of the nanocomposites were performed. In general, the nanocellulose favored the phase separation between the soft and hard domains generating an upward shift in the melting temperatures of the crystalline phases, an increase in the Young's modulus and a decrease in deformation at break. Comparison of the unfilled polymer responses and that of the nanocomposites showed that by increasing cellulose content, increased dynamic storage and tensile modulus as well as melting temperatures and enthalpy of melting of the soft domains can be achieved. Addition of cellulose during the polymerization essentially erased the potential shape memory behavior originally displayed by some of the SPU. However, a sample prepared by adding the cellulose nanocrystals after the reaction showed that the mechanical properties were still improved, while the shape memory behavior of the polymer was preserved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Microbiological and chemical characterization of honeys from central Argentina

The characterization of some honey samples from southern Córdoba (Argentina) was carried out on the basis of their microbiological (Clostridium, fungi and yeasts), physical (colour) and chemical (carbohydrates, HMF, water and free acidity) analysis. The results showed that honeys produced in this region are of good quality. HMF content and free acidity values were mostly low, indicating honey freshness. Most of the samples contained less than 20% water. Glucose and fructose accounted for more than 60% of the weight. The amount of yeast and fungi found in the honey samples was less than 1 × 10² CFU/g. Low quantities of vegetative cells and spores of Clostridia were found in some honey samples. A standardization and a rationalization of beekeeping techniques throughout southern Córdoba may further improve honey quality, and ensure it over the years.     

A comparison between the physico-chemical properties of tuber and cereal starches

Biofilms based on waxy maize and cassava starches (cereal and tuber starch, respectively), plasticized with glycerol were characterized through their crystallinity, dynamic-mechanical behavior (DMA), thermal degradation (TGA), moisture content and water vapor permeability (WVP). X-ray diffraction experiments show that both materials were mainly amorphous, with the waxy starch presenting a discreetly A-type X-ray pattern. Microscopic investigation of the cryo-fractured surfaces supported this observation. The glass transition of the glycerol-rich phase (measured by DMA) occurs at higher temperatures for cassava than for waxy maize starch, suggesting that the dispersion level of glycerol is higher in the former. TGA showed that maize starch has a slightly higher thermal stability than cassava starch, while glycerol interacts more strongly with the last one. The WVP was 18% higher in the case of the cassava starch film.     

Composites from PMMA modified thermosets and chemically treated woodflour

The mechanical behavior of composites made from woodflour and a modified thermoset unsaturated polyester resin has been examined. Polymethylmethacrylate (PMMA), a common low profile additive (LPA), was used as the matrix modifier. Woodflour, the reinforcing filler, was used ‘as received’ and was also modified with a commercial alkenyl succinic anhydride (ASA), in order to enhance the compatibility with the resin. The composites exhibited higher flexural and compressive modulus and compressive yield stress than the neat resin, while flexural strength and ultimate strain were reduced. The addition of PMMA to the unfilled thermoset led to a LPA morphology and decreased the flexural modulus, but produced an increment in flexural strain at break, impact energy and toughness of the UP resin. No enhancement in the mechanical behavior of the composites was found when treated woodflour instead of unmodified woodflour was used.     

In hemodialysis, adiponectin, and pro-brain natriuretic peptide levels may be subjected to variations in body mass index

Adiponectin exerts cardiovascular protective actions, although some studies have shown the opposite. In hemodialysis, obese subjects display lower mortality rates despite hypoadiponectinemia, while higher adiponectin concentrations correlate with an elevated cardiovascular risk in nonobese subjects. The aim of the study is to suggest that adiponectin level variations are associated with differences in the body mass index (BMI). The interplay between adiponectin and pro-brain natriuretic peptide (Pro-BNP) levels may vary according to body fat mass. Fifty-two chronic hemodialysis patients were divided into three groups. Group A, BMI<25 (n=20); Group B, BMI 25 to 30 (n=21), and Group C, BMI>30 (n=11). Diabetics: Group A 10%; Group B 6 29%; Group C 55%, P=0.027. Determinations: Adiponectin, Pro-BNP, insulin, insulin resistance (HOMA), troponin T, nutritional status, ultrafiltration rates, C-reactive protein (CRP), vascular accesses, and echocardiography. Group A: adiponectinemia positively and significantly correlated with Pro-BNP, CRP, and troponin T. As BMI increased, adiponectin, Pro-BNP, and malnutrition significantly decreased, while insulin, HOMA, and ultrafiltration rates significantly increased. Cardiac restriction was significantly higher in obese patients. In all groups, Pro-BNP and troponin T displayed a strong positive correlation. In low-BMI subjects, high Pro-BNP and adiponectin, low myocardial restriction, and worse nutritional status were prevalent. In obesity, hypoadiponectinemia stimulates cardiac remodeling, cardiac hypertrophy, and decreased stretching, rendering Pro-BNP levels low despite high ultrafiltration rates. Thus, adiponectin correlates inversely with BMI, probably playing different cardiovascular roles as BMI changes.     

Chitosan interaction with iron from yoghurt using an in vitro digestive model: comparative study with plant dietary fibers

The objective of this work was to investigate the interaction of chitosan with iron from yoghurt by an in vitro gastrointestinal tract model. Taking into account that chitosan is a polysaccharide included in fiber definition by Codex Alimentarius; chitosan behavior was studied and compared with different plant fiber (wheat, bamboo, apple, psyllium and inulin) behaviors, in the same in vitro conditions. Ferrous sulfate was added to yoghurts with each type of fiber. The gastric environment was simulated with HCl (pH 1.0-2.0). The duodenal environment was simulated with NaHCO(3) (pH 6.8-7.2) and a dialysis tubing cellulose membrane. Results showed that chitosan had the highest iron retention percentages (53.2% at 30 min; 56.8% at 60 min) interacting in a more pronounced manner with iron than the plant fibers used in this work.     

The Minimum Number of Errors in the N-Parity and its Solution with an Incremental Neural Network

The N-dimensional parity problem is frequently a difficult classification task for Neural Networks. We found an expression for the minimum number of errors f as function of N for this problem, performed by a perceptron. We verified this quantity experimentally for N=1,...,15 using an optimal train perceptron. With a constructive approach we solved the full N-dimensional parity problem using a minimal feedforward neural network with a single hidden layer of h=N units.